> I think we can restructure the code a bit to reduce the work involved in adding a new format, though. > Maybe something like this: [snip] Thanks, I’ve applied your obvious refactor in my clone :) For clarity, I will split my patch into many patches for different reports (bug fixes and doc improvements for 3.2, then code cleanup in 3.3, then adding xz). > By the way, is there any reason why you've used ".gz" instead of ".tar.gz" as the extension for "gztar" > in your proposed change? The current version of shutil.py uses ".tar.gz", but has ".bz2" for "bztar". Yes, I confused the two formats. I reported the '.bz2' bug (should be '.tar.bz2') and will fix it. > Also, I notice that _make_tarball() will need to be updated to add the info for xz to the tar_compression > and compress_ext dictionaries. I ripped them off. I could have pasted my full patch to save you time, sorry! > For the "xztar" format, you should also perhaps recognize the ".txz" extension Done. Google finds a number of matches. I won’t add '.tbz' though, as I don’t know if it’s bzip or bzip2, and as it does not seem used much.